Lego plates (all Legos actuallu) are made from ABS plastic, as are plastic shower surround materials. Buy a caulk tube of shower surround adhesive (I have used loctite power grab from Home Depot $5). Scuff the back of the lego plates with some sandpaper and apply the adhesive with a fine notched trowel and slap it on your wood ;) Gently press any lumps out. To date I’ve made 4 lego tables like this and it works wonderfully.